Gallium nitride transistors promise brighter future for LEDs

New advances in transistor technology could make the light-emitting diode (LED) the commercial light source of the future.

Although known for long life and low energy consumption, the LED uses a DC power supply, or driver, to overcome its sensitivity to current fluctuations, and it’s the high-frequency, high-speed switching transistors in this driver that’s made the LED so costly for use in large-scale commercial applications dominated by fluorescent and incandescent lighting.

But that’s about to change. The Fraunhofer Institute for Applied Solid State Physics in Freiburg, Germany, is developing a new, more economical means of making the high-performance gallium nitride transistors needed for the LED’s high-efficiency driver.

The team, led by Dr. Michael Kunzer, group manager at Fraunhofer IAF, has produced a gallium nitride driver with a silicon-beating efficiency of 86 percent.

As well as operating at higher currents, voltages and temperatures, gallium nitride transistors can switch at frequencies up to 10 times faster than their silicon equivalents according to the researchers. This translates to LED lamps that are cheaper, smaller and last longer.

“We have demonstrated the suitability of our gallium nitride transistors for solid-state [LED] lighting,” explains Fraunhofer’s Dr Richard Reiner. “These will improve efficiency, as well as reduce size and costs.”

LED bulbs for use in standard, domestic fittings are available today and “could overtake traditional energy-saving bulbs for the first time by 2015,” according to Fraunhofer.

With old-fashioned incandescent light bulbs banned in the EU and halogen lights facing an uncertain future, LED lighting’s best chance of filling the void is here and now. The LED, says Fraunhofer, “offers a host of advantages as the most environmentally friendly source of light – they contain no harmful substances and consume less energy than other sources.”

LEDs last much longer than their rivals too, with a lifetime of between 15,000 and 30,000 hours compared with 1000 hours for a typical incandescent bulb and 8000 hours for a fluorescent.

The revolution is already underway, according to British trade periodical Lighting, which is forecasting a 45 percent annual growth in the global LED lighting market, reaching US $42 billion – more than half of the global market – by 2019.